Catalytic process for preparing poly-beta-alanine



United States Patent 3,499,874 CATALYTIC PROCESS FOR PREPARING POLY-,s-ALANINE Yasunobu Takahashi and Yohei Fukuoka, Tokyo, Japan, assignors to Asahi Kasei Kogyo Kabushiki Kaisha, Osaka, Japan No Drawing. Filed Oct. 17, 1966, Ser. No. 586,924 Claims priority, application Japan, Oct. 27, 1965, 40/65,462; Nov. 10, 1965, 40/68,526; Feb. 11, 1966, 41/7,720; Mar. 24, 1966, 41/17,640

Int. Cl. C08g 20/06 US. Cl. 260-78 Claims ABSTRACT OF THE DISCLOSURE A poly-fl-alanine is produced by reacting B-aminopropionitrile with water in liquid phase at a temperature of l0250 C. The process can be conducted in the presence of catalysts and solvents and in one embodiment includes reaction in the presence of preformed product polymer.

This invention relates to a process for preparing polyfl-alanine by polymerizing fl-aminopropionitrile in the presence of water.

The fl-aminopropionitrile which is used as a starting material in the process of this invention may be obtained by reacting acrylonitrile with ammoniacal water as described in the Industrial Engineering Chemistry, 50, 1115 (1958). In page 1118 of the above-mentioned publication, it is reported that a water soluble polyamide having a low molecular weight was obtained by polymerizing fl-aminopropionitrile in the presence of a trace of Water, or, under a substantially anhydrous condition, to produce polyamidine compound and subsequently by treating the polyamidine compound thus obtained with water. However, an opaque gel-like polyamide obtained in the process mentioned above was water soluble material having a low molecular weight, of which the chemical structure was not confirmed in the report mentioned above.

An object of this invention is to provide a process for preparing water insoluble poly-fi-alanine from fl-aminopropionitrile.

In accordance with a first aspect of this invention, there is provided a process for preparing poly-fl-alanine by polymerizing fi-aminopropionitrile in the presence of more than about equimolar amount of water per mol of 5- aminopropionitrile at the time of the initiation of the polymerization reaction. If the amount of Water used exceeds 10 mols per mol of ,B-aminopropionitrile, not only the rate of polymerization is decreased but also leads to the production of the polymer having a low degree of polymerization. Thus, the amount of water is preferably less than 3 mols, and most preferably less than 1.5 mols per mol of fi-aminopropionitrile.

In the present process, a reaction temperature of from 10 to 250 C., and most preferably from 60 to 200 C. is used.

If it is desired to prepare poly-fi-alanine in the absence of catalyst under blanket of nitrogen stream according to a process involved in a first aspect of this invention, it is necessary to use a higher part of temperature within the range as prescribed above and a prolonged reaction period for several days to several tens of days, which, nevertheless, produce the badly discolored poly-fi-alanine having a poor degree of polymerization and an unsatisfactorily low purity.

In order to avoid these drawbacks as described above, a second aspect of this invention provides a process for preparing poly-fi-alanine by carrying out the reaction according to the first aspect of this invention in the presence of a catalyst system. By using a catalyst system in the 3,499,874 Patented Mar. 10, 1970 ICC reaction, not only the rate of the polymerization reaction can be remarkably increased but also the reaction period can be greatly shortened. Moreover, the poly-fi-alanine obtained has a pure white color and a high degree of polymerization.

Catalysts which may be used in the present process include, for example, oxides of metals of Cu, Ag, Au, Zn, Cd, Hg, Ce, Ge, Sn, Pb, As, Sb, Bi, Mn, Fe, Co, Ni, Pd and Pt, and inorganic and organic acid salts of said metals such as carbonates, cyanates, thiocyanates, chlorides, bromides, iodides, sulfates, nitrates, formates, acetates, oxalates, p-toluenesulfonates, picrates, monochloroacetates and the like; aliphatic or aromatic primary, secondary and tertiary amines and heterocyclic amines such as ethylamine, dibutylamine, triethylamine, dimethylamine, 2,4- toluenediamine, pyridine, 2 picoline, 3-picoline, 4'picoline, 2,6-lutidine, 2,4,6-collidine, Z-methyl-S-ethylpyridine, morpholine and the like; organic and inorganic acid salts of ammonia and the above-mentioned amines, such as carbonates, sulfates, nitrates, hydrobromides, hydrochlorides, hydrogensulfates, phosphates, formates, acetates, oxalates, monochloroacetates, dichloroacetates, mono methylsulfates and the like; tetraalkylammonium salts such as tetramethylammonium hydrochloride, dirnethylcliethylammonium hydrobromide and the like; organic and inorganic acids such as hydrochloric acid, hydrobromic acid, nitric acid, sulfuric acid, carbon dioxide, formic acid, acetic acid, monochloroacetic acid, dichloroacetic acid, pyridine carboxylic acids; and ozone, peroxides, hydroperoxides, inorganic peracid salts such as hydrogen peroxide, peracetic acid, benzoyl peroxide, tertiary butyl hydroperoxide, potassium persulfate, potassium permanganate and the like.

In the present process, these catalysts exemplified above may be used alone or in the form of a mixture of two or more of these.

The processes described above according to the two aspects of this invention may be carried out in the presence of various solvents, if desired. Solvents which may be preferably used in the processes of this invention include, for example, aromatic hydrocarbons, halogenated aromatic hydrocarbons, ethers, aromatic amines, heterocyclic amines, and the like, such as benzene, toluene, chlorobenzene, xylene, o-dichlorobenzene, dimethylaniline, pyridine, picolines, lutidines, collidines and N-methylmorpholine. In addition to those mentioned above, dialkylformamide, dialkylacetamide, dimethylsulfoxide, tetramethylphosphoramide, tetramethylsulfone and the like may also be used.

In the process according to the second aspect of this invention, catalyst may be charged to a mixture of )3- aminopropionitrile and more than equimolar amount of water per mol of the fi-aminopropionitrile either by adding the total amount of the catalyst required in the reaction at the time of the initiation of the reaction or by adding portionwise intermittently in the course of the reaction. The catalyst may either be in the form of a solution or of a suspension in a suitable medium. The amount of catalyst used is preferably from 0.0001 to 1 mol per mol of fl-aminoproprionitrile.

The products obtained in the processes described above are finely divided, successively washed with alcohol, cold and hot Water, and dried.

The products thus obtained were identified to be poly- B-alanine by an infrared absorption spectrum, an elementary analysis, the formation of fi-alanine by hydrolysis and paper chromatographic analysis thereof. The viscosity of the poly-fi-alanine was measured by dissolving 0.1 g. of the dried polymer in 10 ml. of dichloroacetic acid or formic acid at C.

In order to increase the yield of water insoluble polyfi-alanin'e 'anclthe rate of polymerization, the processes according -to a third and afourth aspect of this invention as described hereinafter are extremely effective.

The process according to the third aspect of this invention comprises reacting B-aminopropionitrile with weight of said poly-B-alanine up to a higher degree. The supply ofwater to the reaction system may either be accomplished by steam alone or by a mixture consisting of steam and an inert gas. Further, if desired, the reaction may be carried out by suspending poly-fi-alanine in a more than an 'equimolar amount of water in the presence 5 suitable organic solvent as mentioned hereinbefore. of a reaction mixture'containing poly-fi-alanine obtained In accordance with the presentprocess, the hot water in the'process according to the second-aspect of this ininsolubles contained in the product .poly-fl-alanine may vention as a catalyst in the present process. 'be increased to more than 90% and also the average Although no :particular .restriction is imposed on the reduced specific viscosity of the product may be increased reaction mixture used as a catalyst, in eneral, areaction to more than 0.2. .mixture'containing poly-fl-alanine having relatively lower These processes according -.to the first through the degree'of'polymerization,'e.g. a-reduced specific viscosity fourth aspects of this invention 'as'illustrated above proof less than 0.05, may be conveniently used because of duce poly-'B-alanine havinga higher degree of polymerizathe compatibilitythereof 'to ,B-aminopropionitrileand the tion in a more stabilizedfas hionascompared with prior good dispersibility 'therein. art processes for preparing poly-fl-alanine from acryl- Since poly-fi-alanine having a'reduced specific viscosity amide or ethylenecyanohydrin. of higher'than 0.05 usuallytakes the -form of solid or gel- Poly-fl-alanine obtained za'c'cordingto the processes of like solid, it is necessary to disperse it thoroughly into the this invention may be used asa starting material-for proreactant mixture containing fi-amino-propionitrile by ducing fibers, films and other shaped articles which are grinding, kneading and stirring when using a reaction commercially useful. mixture containing such poly-fi-alanine as a catalyst. Thefollowing examples will serve to illustrate the proc- The amount of the reaction mixture containing polyesses of this invention more practically. However, it flalanine used is preferably from 0.0001 to 10 parts'by should not be'construed that these examples restrict this weight :per part by weight of fl-aminopropionitrile to 'be invention as they are'givenmerely by way of illustration. polymerized 'in'this process. Theprocess according to'th'e :EXAMPEE 1 third aspect of this invention explained above may, of -course,'be carried out in the presence of solvent asexem- A 'fi consisting of 7 gof fi-aminopmpionhfile lifi d b and 1.8 g. of water was allowed to stand-still for 15 days The catalyzing effects .of the catalyst used in the procat 33 -C. anda lactescent solid was obtained. The solid ess according to the third aspect of this invention are as thu a C Washed With methanol and hot Water, much as or'more than 100 times than that of the process d dried g v .g- 'of'white Solid- An infrared according to the second aspect of this invention at a given sorption spectrum of the solid showed the disappearance amount of catalyst-Furthermore, since a smaller amount of absorp at 1505 (P y amine) and of catalyst may be required in the present process to ob- 2300 cm. (Ilitfile :g P), and an absorption at 1640 tain a given catalyzing effect, the purification of the polycm.- 2(amide group) was observed. Values of an elefi-alanine and the subsequent operations such as Spinning mentary analysis were C, 50.11%; H, 7.28% and N, maybe-made mucheasier. This gives, as a result, a great 20.04%. Calculated values for poly-fl-alanine (C H ON) advantage from a commercial point of view in that polywere C, 50.69%;-H, 7.09% and N, 19.71%. fl-alanine having better physical properties may be ob- 40 Further, 0.3 -g.-of the product polymer was-hydrolyzed tained, which, in turn, leads to .the production of shaped with 5 ml. of concentrated hydrochloricacid at 120 C. articles, for example, fibers having excellent .physical for-2 hours and after the resulting product was neutralproperties. ized and concentrated, -paper-chromatographic analysis .Another process according to a fourth aspect of the wascohducted y using Phenohwatfir y As a result, present invention enables a great increase in the yield of the was '0151 which coincided with that of til-alanine hot water insoluble poly-fl-alanine having a high degree dweloped at the Same time- The P y had'a reduced of l i i specific viscosity of 0.17 as measured by dissolving 0.1 g. Although water'soluble poly-'B-alanine oligomer having 0f Lhe-Phldlwt Polymer-in 10 of dichlofoacefic acida lowdegree of polymerization has various utilities in r H itself, the formation thereof is rather undesirable in the EXAMPLES 244 commercial production of high molecular Weight poly-fi- Example 1 was repeated according to the same procealanine. dures as described therein except that various amounts Thus, the present process according to a fourth aspect of B-arninopropionitrile, water and catalyst, various types of this invention comprises heating poly-fl-alanine obof catalyst as specified-inthe'following table, and various tained in the processes according-to thepreceding aspects reaction temperatures and-periodsalso as specified in the of this invention in a closed vessel at a temperature of following table were employed. The resulting reaction from 80 to 250 C., and most preferably from 120 to mixtures were treated-according-to the same procedures 200 C. for more than an hour, and most preferably .24 as in Example 1 and the yields and reduced specific visto 200 hours, under-an elevated pressure in the presence cosities of the .products poly-fl-alanine \WCIC measured, of sufficient amount of water to jump the molecular respectively. The-results are shown in the following table:

Reduced B-Amino- Reaction specific proprotemper- Reaction viscosity nitr1le,;g. Water, g. Catalyst Mg. ature, 0. period Yield, g. 1; sp./c Example No.:

2 l4 5 SnCh-2Hz0 25 40 3days 5.8 0.37 14 13 R1600: 1.4 -80 Zdays 4.4 0.35 14 74.0 230440 7days 2.1 0.18 14 -3.9 Hg(CH;COO)a 10 20 3days 5.9 0.42 28 10 011011 5 to 501mm. 12.6 0.36 28 10 1, 40 31 fiohours. 12.1 0.36 28 14 H g(CHiCOO)1 28 50 55 hours 13.1 0.40 28 13 Bl(NO8)3-5H1O 15 a0 50hours- 9.4 0.29 28 10 Ce(NOa)1-2NH4NOs 20 50 55 hours 8.9 0.27 14 3.9 KMnoi 10 20 3'days 4.4 0. 34 14 5 211003 5 40 do 6.0 0.41 14 5 Hg(SCN)i 8 40 do. 6.4 0.43 14 5 Z 10 40 6.2 0.40

A mixture consisting of 14.0 g. of B-aminopropionitrile, various amounts of water and various types and amounts of catalysts as specified in the following table was subjected to the polymerization reactions at 32 C. for 240 hours in a nitrogen atmosphere and the time required for the product to solidify, the yield of dried polymer obtained by washing the crude polymer with cold and hot water and methanol followed by drying, and the reduced specific viscosities of the dried polymer as measured by dissolving 0.1 g. of the same in ml. of dichloroacetic acid are shown in the following table.

As controls, Examples and 16 show the results obtained without using any catalyst.

6 EXAMPE 39 10 After the completion of the reaction, the autoclave was unsealed to take out the polymerization product, which was then crushed and treated with hot water, and the insolubles thus obtained were dried to give 49 g. of dried polymer.

Example Nos.

BAminopropionitrile, g 0 14. 0 14. 14. 0 14. 0 14. 0 41. 0 14. 0 14. 0 14. 0 14. 0 14. 0 ,g .0 6.0 8. 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 Type of wtalyst (2) (a) (4) (s) m (1) (1) (s) (0) (10) (u) (12) Amount of catalyst, m 0 10. 0 13. 13. 0 2. 0 2. 0 0. 4 10. 0 2. 0 10. 0 5. 0 10. 0 Time required for solidifying, hr- 77 79 62 63 46 2 49 51 64 83 47 72 Yield of dried polymer, g 2. 8 3. 7 3. 4. 0 5. 3 6. 0 6. 1 4. 4 4. 1 4. 7 4. 4 4. 2 Reduced specific viscosity 0. 29 0. 25 0. 32 0. 0. 0. 41 0. 37 0. 34 0. 34 0. 31 0. 29 0. 28 0. 24

1 Ammonium fluoride.

2 Ammonium rhodanate.

Dimethyl aniline.

4 Dimethylaniline hydrochloride. 5 a-picolinedichloroacetate.

6 Peracetic acid. Pyridine.

EXAMPLES 30-3 8 A mixture consisting of 8.0 g. of B-aminopropionitrile, 2.0 g. of water and 10 mg. of various types of catalyst as specified in the following table shown as (A) therein or 1.0 g. of poly-fl-alanine shown as (B) therein, as a catalyst, was subjected to the polymerization reactions at 15 C. for 42 hours in a nitrogen stream and the conversion, yields and reduced specific viscosities of the respective product polymers were measured.

Poly-,B-alanine shown as (B) in the table mentioned above which was used as a catalyst consisted mainly of water soluble polymer and it was prepared by reacting 8.0 g. of fi-aminopropionitrile with 2.0 g. of water at 45 C. for 30 hours in a nitrogen atmosphere in the presence of 10 mg. of catalyst shown as (A) in each example.

The yields mentioned above and shown in the table were measured by weighing the dried water insoluble polymers obtained by heating the crude polymer at 45 C. for an additional 48 hours, treating the resulting polymer with hot Water and drying.

The reduced specific viscosities referred to in the table were measured by dissolving 0.1 g. of the dried polymers in dichloroacetic acid.

1 Hydrogen peroxide. 8 Benzoyl peroxide Tertiary butyl hydro peroxide. Tri-n-butyl amine.

Potassium persulfate.

The dried polymer had a reduced specific viscosity of 0.24 as measured by dissolving 0.1 g. of the same in 10 cc. of dichloroacetic acid.

EXAMPLE 40 A mixture consisting of g. of fi-aminopropionitrile, 20 g. of water and 0.1 g. of ammonium sulfate was allowed to stand still at 28-35 C. for 50 hours and a lactescent wax-like solid was obtained. The solid thus obtained was transferred to an autoclave and after adding 2.0 g. of water thereto, the content was treated in the wetted condition at 180 C. for 5 days under seal. After the completion of the reaction, the autoclave was unsealed to take out the polymerization product, which was crushed and treated with hot water, and insolubles were dried to give 79 g. of dried polymer. The dried polymer had a reduced specific viscosity of 0.32.

EXAMPLE 41 A mixture consisting of g. of B-aminopropionitrile, 50 g. of water and 0.2 g. of 40% peracetic acid was heated in an autoclave at 6065 C. for 46 hours to give a lactescent solid. The product solid was finely divided and charged in a tubular heater provided with a jacket and,

5 while maintaining the jacket temperature at C., an

Amount of catalyst Conversion based on after Water insoluble the weight 42 hrs. polymer of fi-aminofrom the propionitrile starting Reduced Example and water of specific No. Type of catalyst charged, percent reaction Yield, g. viscosity 30 {.A, ammonium carbonate 0. 1 2 1. 9 0. 21 B, poly-fi-alamne-. 0. 01 28 3. 7 0. 27 31 {A, cupric chloride 0. 1 7 2. 6 0. 25 B, poly-B-alanine 0. 01 43 4. 6 0.37 32 {.A, cobalt acetate- 0.1 2 1. 7 0. 19 B, poly-fl-alanme... 0.01 15 3.4 0.23 33 A, potassium permanganate.. 0. 1 2 1. 3 0. 14 B, poly-,B-alanine 0.01 11 3.5 0.25 34 A, monoehloroacetic acid 0. 1 3 2. 8 0. 24 B, poly-B-alanine".-. 0.01 24 4.4 0.30 35 A, hexamethylenediamine carbonate- 0. 1 2 2. 4 0. 18 B, poly'B-a1anine. 0.01 15 3.8 0.23 36 A, o peracetic ac 0. 1 2 2. 5 0.25 B, poly-B-alanine 0. 01 32 4. 1 0. 36 37 {A, 33% hydrogen peroxide 0. 1 3 3. 0 0. 20 B, poly-B-alanine-.. 0. 01 28 4. 3 0. 41 38 A, dimethylaniline" 0. 1 2 2. 8 0. 22 B, poiy-fl-alaniue.-.---- 0.01 21 4.1 0.34

overheated steam heated to a'temp'erature of 170 C. in a preheater was allowed to pass therethrough for about 100 hours. After'th'e polymer was dried and'treated with ho't'water, the insolubles were dried'to give 158 g. of dried polymer having a're'duced specific viscosity of 0.40.

EXAMPLE 42 A-mixture consisting of '70 g. of fi-aminopropionitrile, 18.2 g.-of water and 350 mg. of zinc dichloride as a catalyst was allowed to stand still for 60 hours and a lactescent gel-like solid was obtained. The solid was found to'have a reduced specific viscosity of 0.08. To each portion-of 1.0 g. of solid thus obtained was added 1 ml. each'o'f solvents asspecified in the-following table, respectively, and the resulting mixture was allowed to stand still in a sealed tube at 170 C. for 40 hours.

At the end of the period, the tube was unsealed and the polymerization product was filtered and washed with methanol, cold and hot water followed by drying to give solid products. The results are shown in the following table:

EXAMPLE '43 A mixture consisting of 7 g. of fi-a-minopropionitrile, l'.'82"g; of water, 0.035 gof zinc-dibromide, 'as'a catalyst, and 9 ml. ofsolvent as specified in the following'ta'ble was reacted-at 170C. for 40'hours in a nitrogen stream.

To' the'reaction mixtures'were added 20 ml. of methanol and thepdlymerization products were filtered and washed with cold and'hot water and dried to give white solids.

The results are given in the following table:

Yield 01 water Reduced insoluble specific polymer, viscosity, Type of solvent percent nspJc.

(1) Dimethylt'ormamide 53 0.25 (2) Dimethylphosphoramrde. 62 0.18 (3) N-methylmorpholme 100 0.28 (4) 'y-Picoline 82 0.25 (5) Chlor0benzene 87 0.23 (6) Dimethylaniline 82 0.21 (7) '1,2,4-trichlorobenzene -87 0.

What we claim is:

1. Process for preparing solid polymeric poly-fi-alanine which comprises reacting in liquid phase fi-arnino-propionitrile with water in the presence of a catalyst at a temperature of from 10 to 250 C., the amount of water used being in excess of about 1 mol and-up to'1 0 mols per mol of fl-aminopropionitrile, said catalyst being used in the amount of 0.0001 to 1 molpermol of p-arninopropionitrile, said catalystbeing at least one member selected from the group consisting of oxides of Cu, Ag, Au, Zn, Cd, Hg, Ce,-Ge, Sn,Pb, As, Sb, Bi, Mn, Fe,-Co, Ni, Pd and 'Pt, inorganic and organic acid salts of said metals, aliphatic and aromatic primary, secondary and tertiary amines, heterocyclic amines, organic and inorganic acid salts of ammonia and'the above'mentioned amines, tetraalkyl ammonium salts, organic and inorganic acids, ozone, peroxides, hydroperoxides, and inorganic peracid salts.

2. A process according to claim v1, wherein the reaction is carried out in the presence of an amount of preformed poly-B-alanine which is s'uflicient to increase the rate of the reaction, said preformed poly-B-alanine having been prepared by reacting in liquid -phase fl-amino-pro- 'pionitrile in water at 10 to 250C. in the presence of a catalyst as defined in claim 1, the amount of water being in'excess of-about 1 mol and up to about '10 mols per molof fl-amino-propionitrile.

3. A process according to 'claim '2, wherein said preformed poly-B-alanine has a reduced specifi'c'viscosity of less than about 0.05 as determined by dissolving 0.1 gram of the polymer in 10 ml. of-dichloroacetic acid at C.

4. Process according toclaim 1 wherein said preformed poly-fi-alanine is used in an amount of from 0.0001 to 10 parts by weight per .part by weight of B-arninopropionitrile.

5. Process according to claim -1 wherein the reaction is carried out in a solvent selected from the .group consisting of aromatic hydrocarbons, halogenated aromatic hydrocarbons, ethers, aromatic amines, heterocyclic amines, dialkylformamide, dialkylacetamide, dimethylsulfoxide, tetramethylphosphoramide and tetramethylsulfone.

References Cited UNITED STATES =PAT-ENTS 2,071,253 2/ 1937 "CarOth'ers 260-78 2,245,129 6/ 1941 Greenewalt 260-78 2,691,643 10/1954 'Chirtel et"al. 260-78 2,301,964 11/1942 Martin 260-239 2,357,484 9/1944 Martin 260-239 HAROLD D. ANDERSON, Primary'Examin'er US. Cl. X.R. 

